Ideal magnetic quadrupole radiators.

High-purity magnetic quadrupole (MQ) radiation is fundamentally limited by ultralow radiative transition rates and severe mode mixing. Here, we propose a synergistic strategy combining parity-selective mode filtering and anapole engineering to realize ideal MQ radiation. Our design achieves an MQ mode-purity-factor (MPF) exceeding 99.5% under both far-field plane-wave and near-field dipole excitations. Critically, this mechanism enables the direct, contamination-free conversion of fundamental electric dipole (ED) emission into pure MQ radiation. This work establishes a robust paradigm for deterministic high-order magnetic multipole manipulation, with immediate applications in quantum light sources and topological photonics.